Diagnosing Osteoarthritis of the Shoulder

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Specialists at NYU Langone use advanced imaging tests to diagnose osteoarthritis of the shoulder, a progressive condition that causes aching pain, stiffness, and limited range of motion in the shoulder joint.

The shoulder has two joints that work together to give your arm its full range of flexibility and motion. The larger joint, called the glenohumeral joint, is located where the arm bone fits into your shoulder blade. The glenohumeral joint is a ball-and-socket joint, meaning that the round end of the arm bone, called the humerus, fits into a socket in your shoulder blade, called the glenoid cavity. The smaller joint, called the acromioclavicular joint, is located where your collarbone meets the tip of your shoulder blade.

The ends of the bones in the shoulder joint are lined with a firm, smooth material called cartilage, which helps the bones move easily against each other when the arm is in motion. Cartilage also protects the bones from rubbing directly against each other.

The cause of shoulder pain and other osteoarthritis symptoms is often friction between bones that occurs when cartilage erodes. If enough cartilage wears away, bone-on-bone contact can prevent the joint from working properly, limiting your ability to move your shoulder easily. Friction in the joint can also lead to the development of bony growths, called bone spurs, that interfere with smooth joint motion and rub painfully against exposed bone. Bone spurs may also restrict movement in the shoulder joint, limiting your ability to move your arm.

New research suggests that osteoarthritis symptoms may also occur as a result of inflammation in the synovium, a membrane that lines the shoulder joint. In a healthy shoulder, the synovium secretes a gel-like substance called synovial fluid that lubricates the joint and helps absorb stress during movement.

Pain and stiffness related to osteoarthritis have been linked to a thinning of synovial fluid, which further contributes to joint degeneration.

Causes and Symptoms

Most of the time, osteoarthritis affects people older than age 60, whether symptoms are associated with the “wear and tear” of gradual cartilage erosion, the thinning of synovial fluid, or both. In younger people, osteoarthritis of the shoulder may develop because of long-term repetitive use of the joint. For example, a professional weight lifter may experience premature osteoarthritis, because years of forceful movement in the shoulder slowly wear down the cartilage. An injury or surgery in the shoulder can damage cartilage and lead to further cartilage degeneration and osteoarthritis. Osteoarthritis can also run in families.

The most common symptom of osteoarthritis of the shoulder is aching pain in the joint that gets worse when you move your arm. You may notice that everyday motions, such as brushing your teeth or holding a child, cause discomfort. As osteoarthritis advances, pain may be present even while you’re at rest, limiting the range of motion in your shoulder—for example, you may have trouble putting on a jacket.

Early diagnosis is important; if arthritis pain limits your ability to move the affected shoulder, the muscles in that shoulder weaken, which can limit the range of motion even more.

Experts at NYU Langone’s Joint Preservation and Arthritis Center understand that osteoarthritis in the shoulder can hamper many activities in your daily routine and that persistent pain can diminish your quality of life. Our shoulder experts recognize the signs and symptoms of osteoarthritis, even if joint damage is mild, and distinguish between osteoarthritis and other shoulder injuries, such as a tear in a ligament.

Medical History

A doctor may ask you about your medical history and whether other members of your family have been diagnosed with arthritis. He or she also asks about your symptoms, such as when you first noticed pain or stiffness, whether you feel discomfort all the time or only during certain times of day, whether pain keeps you from moving your arm in certain ways, whether you hear a grinding or clicking sound when you move your arm, or whether pain or other symptoms have affected your ability to perform daily tasks.

Doctors also ask for details about any other medical conditions you have and whether they require medication. If you injured your shoulder previously or have had shoulder surgery, you may have a higher risk of developing osteoarthritis, especially if cartilage was damaged at that time.

Physical Exam

During a physical exam, your doctor visually examines your shoulder for signs of osteoarthritis. He or she may carefully move your shoulder and arm to assess the range of motion and listen for any cracking or popping noises in the joint, called crepitus, that may indicate joint damage. Your doctor may put gentle pressure on the shoulder to test your level of discomfort and determine whether the location of the pain you feel results from movement in the joint.

A shoulder injury such as a torn ligament may cause similar symptoms, and our doctors can distinguish between osteoarthritis and another type of shoulder injury.

X-rays

X-rays provide detailed images of the shoulder joint and can reveal the presence of cartilage damage. Doctors can see evidence of cartilage erosion by looking at the space between the bones in the shoulder joint.

A healthy shoulder joint appears to have a gap between the bones on an X-ray because a layer of cartilage lines the ends of the bones and prevents them from rubbing directly against each other. In an arthritic joint, this gap between bones is narrowed, indicating a loss of cartilage. In an arthritic shoulder, the shape of the bones may also be less smooth or less round.

X-rays may also reveal bony growths in the joint, a classic sign of osteoarthritis. These bone spurs develop as part of the body’s response to the friction caused by diminishing cartilage.

Patient-Reported Outcome Score

As part of the diagnostic process, doctors at NYU Langone use a measurement called a patient-reported outcome score to assess your shoulder pain and joint function. Doctors use a questionnaire to obtain information about your symptoms and whether they prevent you from participating in everyday activities, how much they affect your quality of life, and whether you’ve limited your participation in sports or exercise because of arthritis. This questionnaire can be completed online before visiting the NYU Langone facility, on an iPad while at the facility, or on paper.

Information from the questionnaire helps doctors use the results of imaging tests in creating a customized treatment plan. For example, some people may not show joint damage on an X-ray but still have chronic pain. Others feel little or no pain even though an X-ray reveals significant cartilage erosion.

By using the patient-reported outcome tool, our arthritis experts ensure that treatment is not solely based on diagnostic tests.

Ultrasound and MRI

A doctor may recommend an ultrasound or MRI scan to evaluate inflammation in soft tissues, such as the synovium, that cannot be seen on X-ray. These imaging tests can also reveal accumulation of fluid in the joint.

Ultrasound or MRI may also be used if your doctor suspects that the pain in your shoulder joint is caused by something other than osteoarthritis. For example, an injury to the muscles or tendons in the shoulder or neck may cause shoulder pain that feels similar to the discomfort associated with osteoarthritis. An ultrasound or MRI scan can confirm if a shoulder tear, neck strain, or other soft tissue injury is present.

During an ultrasound, high-frequency sound waves are used to create images of structures inside the body. This exam often takes place at the same time as a physical exam in the doctor’s office. MRI scanning uses magnetic fields and radio waves to produce detailed two- or three-dimensional images that allow doctors to examine the shoulder from a variety of angles.

Arthrocentesis

If your symptoms include swelling, warmth, or redness, the cause may be fluid in the shoulder joint. Your doctor may recommend a procedure called arthrocentesis to remove it. This may relieve pain and swelling, and a doctor may also send a small amount of fluid to a laboratory for testing. The results can rule out other possible causes of joint pain, such as gout, infection, or rheumatoid arthritis, a form of arthritis that typically affects multiple joints at once.

To perform arthrocentesis, your doctor injects a local anesthetic to numb the skin, then guides a needle carefully into the joint space where fluid has accumulated. The doctor removes fluid and sends it to the lab for testing. Results are typically available within three days.

Joint fluid can also be analyzed for biomarkers in those who want to participate in the Joint Preservation Registry, an advanced research program being conducted at NYU Langone. Arthritis specialists evaluate substances present in joint fluid to identify individual patterns of disease and tailor treatment to relieve shoulder osteoarthritis symptoms.

NYU Langone orthopedic surgeons at the Joint Preservation and Arthritis Center are actively involved in research to incorporate biomarker testing into plans of care.